<?php

abstract class WebSocketServer {

	protected $userClass = 'WebSocketUser'; // redefine this if you want a custom user class.  The custom user class should inherit from WebSocketUser.
	protected $maxBufferSize;
	protected $master;
	protected $sockets                              = array();
	protected $users                                = array();
	protected $interactive                          = true;
	protected $headerOriginRequired                 = false;
	protected $headerSecWebSocketProtocolRequired   = false;
	protected $headerSecWebSocketExtensionsRequired = false;

	function __construct($addr, $port, $bufferLength = 2048) {
		$this->maxBufferSize = $bufferLength;
		$this->master = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)  or die("Failed: socket_create()");
		socket_set_option($this->master, SOL_SOCKET, SO_REUSEADDR, 1) or die("Failed: socket_option()");
		socket_bind($this->master, $addr, $port)                      or die("Failed: socket_bind()");
		socket_listen($this->master,20)                               or die("Failed: socket_listen()");
		$this->sockets[] = $this->master;
		$this->stdout("Server started\nListening on: $addr:$port\nMaster socket: ".$this->master);

		while(true) {
			if (empty($this->sockets)) {
				$this->sockets[] = $master;
			}
			$read = $this->sockets;
			$write = $except = null;
			@socket_select($read,$write,$except,null);
			foreach ($read as $socket) {
				if ($socket == $this->master) {
					$client = socket_accept($socket);
					if ($client < 0) {
						$this->stderr("Failed: socket_accept()");
						continue;
					} else {
						$this->connect($client);
					}
				} else {
					$numBytes = @socket_recv($socket,$buffer,$this->maxBufferSize,0); // todo: if($numBytes === false) { error handling } elseif ($numBytes === 0) { remote client disconected }
					if ($numBytes == 0) {
						$this->disconnect($socket);
					} else {
						$user = $this->getUserBySocket($socket);
						if (!$user->handshake) {
							$this->doHandshake($user,$buffer);
						} else {
							if ($message = $this->deframe($buffer, $user)) {
								$this->process($user, utf8_encode($message));
								if($user->hasSentClose) {
									$this->disconnect($user->socket);
								}
							} else {
								do {
									$numByte = @socket_recv($socket,$buffer,$this->maxBufferSize,MSG_PEEK);
									if ($numByte > 0) {
										$numByte = @socket_recv($socket,$buffer,$this->maxBufferSize,0);
										if ($message = $this->deframe($buffer,$user)) {
											$this->process($user,$message);
											if($user->hasSentClose) {
												$this->disconnect($user->socket);
											}
										}
									}
								} while($numByte > 0);
							}
						}
					}
				}
			}
		}
	}

	abstract protected function process($user,$message); // Calked immediately when the data is recieved.
	abstract protected function connected($user);        // Called after the handshake response is sent to the client.
	abstract protected function closed($user);           // Called after the connection is closed.
	abstract protected function traiterBalReiv();

	protected function connecting($user) {
		// Override to handle a connecting user, after the instance of the User is created, but before
		// the handshake has completed.
	}

	protected function send($user,$message) {
		$this->stdout("> $message");
		$message = $this->frame($message,$user);
		socket_write($user->socket,$message,strlen($message));
	}

	protected function connect($socket) {
		$user = new $this->userClass(uniqid(),$socket);
		array_push($this->users,$user);
		array_push($this->sockets,$socket);
		$this->connecting($user);
	}

	protected function disconnect($socket,$triggerClosed=true) {
		$foundUser = null;
		$foundSocket = null;
		foreach ($this->users as $key => $user) {
			if ($user->socket == $socket) {
				$foundUser = $key;
				$disconnectedUser = $user;
				break;
			}
		}
		if ($foundUser !== null) {
			unset($this->users[$foundUser]);
			$this->users = array_values($this->users);
		}
		foreach ($this->sockets as $key => $sock) {
			if ($sock == $socket) {
				$foundSocket = $key;
				break;
			}
		}
		if ($foundSocket !== null) {
			unset($this->sockets[$foundSocket]);
			$this->sockets = array_values($this->sockets);
		}
		if ($triggerClosed) {
			$this->closed($disconnectedUser);
		}
	}

	protected function doHandshake($user, $buffer) {
		$magicGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
		$headers = array();
		$lines = explode("\n",$buffer);
		foreach ($lines as $line) {
			if (strpos($line,":") !== false) {
				$header = explode(":",$line,2);
				$headers[strtolower(trim($header[0]))] = trim($header[1]);
			} else if (stripos($line,"get ") !== false) {
				preg_match("/GET (.*) HTTP/i", $buffer, $reqResource);
				$headers['get'] = trim($reqResource[1]);
			}
		}
		if (isset($headers['get'])) {
			$user->requestedResource = $headers['get'];
		} else {
			// todo: fail the connection
			$handshakeResponse = "HTTP/1.1 405 Method Not Allowed\r\n\r\n";
		}
		if (!isset($headers['host']) || !$this->checkHost($headers['host'])) {
			$handshakeResponse = "HTTP/1.1 400 Bad Request";
		}
		if (!isset($headers['upgrade']) || strtolower($headers['upgrade']) != 'websocket') {
			$handshakeResponse = "HTTP/1.1 400 Bad Request";
		}
		if (!isset($headers['connection']) || strpos(strtolower($headers['connection']), 'upgrade') === FALSE) {
			$handshakeResponse = "HTTP/1.1 400 Bad Request";
		}
		if (!isset($headers['sec-websocket-key'])) {
			$handshakeResponse = "HTTP/1.1 400 Bad Request";
		} else {

		}
		if (!isset($headers['sec-websocket-version']) || strtolower($headers['sec-websocket-version']) != 13) {
			$handshakeResponse = "HTTP/1.1 426 Upgrade Required\r\nSec-WebSocketVersion: 13";
		}
		if (($this->headerOriginRequired && !isset($headers['origin']) ) || ($this->headerOriginRequired && !$this->checkOrigin($headers['origin']))) {
			$handshakeResponse = "HTTP/1.1 403 Forbidden";
		}
		if (($this->headerSecWebSocketProtocolRequired && !isset($headers['sec-websocket-protocol'])) || ($this->headerSecWebSocketProtocolRequired && !$this->checkWebsocProtocol($header['sec-websocket-protocol']))) {
			$handshakeResponse = "HTTP/1.1 400 Bad Request";
		}
		if (($this->headerSecWebSocketExtensionsRequired && !isset($headers['sec-websocket-extensions'])) || ($this->headerSecWebSocketExtensionsRequired && !$this->checkWebsocExtensions($header['sec-websocket-extensions']))) {
			$handshakeResponse = "HTTP/1.1 400 Bad Request";
		}

		// Done verifying the _required_ headers and optionally required headers.

		if (isset($handshakeResponse)) {
			socket_write($user->socket,$handshakeResponse,strlen($handshakeResponse));
			$this->disconnect($user->socket);
			return false;
		}

		$user->headers = $headers;
		$user->handshake = $buffer;

		$webSocketKeyHash = sha1($headers['sec-websocket-key'] . $magicGUID);

		$rawToken = "";
		for ($i = 0; $i < 20; $i++) {
			$rawToken .= chr(hexdec(substr($webSocketKeyHash,$i*2, 2)));
		}
		$handshakeToken = base64_encode($rawToken) . "\r\n";

		$subProtocol = (isset($headers['sec-websocket-protocol'])) ? $this->processProtocol($headers['sec-websocket-protocol']) : "";
		$extensions = (isset($headers['sec-websocket-extensions'])) ? $this->processExtensions($headers['sec-websocket-extensions']) : "";

		$handshakeResponse = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: $handshakeToken$subProtocol$extensions\r\n";
		socket_write($user->socket,$handshakeResponse,strlen($handshakeResponse));
		$this->connected($user);
	}

	protected function checkHost($hostName) {
		return true; // Override and return false if the host is not one that you would expect.
		// Ex: You only want to accept hosts from the my-domain.com domain,
		// but you receive a host from malicious-site.com instead.
	}

	protected function checkOrigin($origin) {
		return true; // Override and return false if the origin is not one that you would expect.
	}

	protected function checkWebsocProtocol($protocol) {
		return true; // Override and return false if a protocol is not found that you would expect.
	}

	protected function checkWebsocExtensions($extensions) {
		return true; // Override and return false if an extension is not found that you would expect.
	}

	protected function processProtocol($protocol) {
		return ""; // return either "Sec-WebSocket-Protocol: SelectedProtocolFromClientList\r\n" or return an empty string.
		// The carriage return/newline combo must appear at the end of a non-empty string, and must not
		// appear at the beginning of the string nor in an otherwise empty string, or it will be considered part of
		// the response body, which will trigger an error in the client as it will not be formatted correctly.
	}

	protected function processExtensions($extensions) {
		return ""; // return either "Sec-WebSocket-Extensions: SelectedExtensions\r\n" or return an empty string.
	}

	protected function getUserBySocket($socket) {
		foreach ($this->users as $user) {
			if ($user->socket == $socket) {
				return $user;
			}
		}
		return null;
	}

	protected function stdout($message) {
		if ($this->interactive) {
			echo "$message\n";
		}
	}

	protected function stderr($message) {
		if ($this->interactive) {
			echo "$message\n";
		}
	}

	protected function frame($message, $user, $messageType='text', $messageContinues=false) {
		switch ($messageType) {
			case 'continuous':
				$b1 = 0;
				break;
			case 'text':
				$b1 = ($user->sendingContinuous) ? 0 : 1;
				break;
			case 'binary':
				$b1 = ($user->sendingContinuous) ? 0 : 2;
				break;
			case 'close':
				$b1 = 8;
				break;
			case 'ping':
				$b1 = 9;
				break;
			case 'pong':
				$b1 = 10;
				break;
		}
		if ($messageContinues) {
			$user->sendingContinuous = true;
		} else {
			$b1 += 128;
			$user->sendingContinuous = false;
		}

		$length = strlen($message);
		$lengthField = "";
		if ($length < 126) {
			$b2 = $length;
		} elseif ($length <= 65536) {
			$b2 = 126;
			$hexLength = dechex($length);
			//$this->stdout("Hex Length: $hexLength");
			if (strlen($hexLength)%2 == 1) {
				$hexLength = '0' . $hexLength;
			}
			$n = strlen($hexLength) - 2;

			for ($i = $n; $i >= 0; $i=$i-2) {
				$lengthField = chr(hexdec(substr($hexLength, $i, 2))) . $lengthField;
			}
			while (strlen($lengthField) < 2) {
				$lengthField = chr(0) . $lengthField;
			}
		} else {
			$b2 = 127;
			$hexLength = dechex($length);
			if (strlen($hexLength)%2 == 1) {
				$hexLength = '0' . $hexLength;
			}
			$n = strlen($hexLength) - 2;

			for ($i = $n; $i >= 0; $i=$i-2) {
				$lengthField = chr(hexdec(substr($hexLength, $i, 2))) . $lengthField;
			}
			while (strlen($lengthField) < 8) {
				$lengthField = chr(0) . $lengthField;
			}
		}

		return chr($b1) . chr($b2) . $lengthField . $message;
	}

	protected function deframe($message, $user) {
		//echo $this->strtohex($message);
		$headers = $this->extractHeaders($message);
		$pongReply = false;
		$willClose = false;
		switch($headers['opcode']) {
			case 0:
			case 1:
			case 2:
				break;
			case 8:
				// todo: close the connection
				$user->hasSentClose = true;
				return "";
			case 9:
				$pongReply = true;
			case 10:
				break;
			default:
				//$this->disconnect($user); // todo: fail connection
				$willClose = true;
				break;
		}

		if ($user->handlingPartialPacket) {
			$message = $user->partialBuffer . $message;
			$user->handlingPartialPacket = false;
			return $this->deframe($message, $user);
		}

		if ($this->checkRSVBits($headers,$user)) {
			return false;
		}

		if ($willClose) {
			// todo: fail the connection
			return false;
		}

		$payload = $user->partialMessage . $this->extractPayload($message,$headers);

		if ($pongReply) {
			$reply = $this->frame($payload,$user,'pong');
			socket_write($user->socket,$reply,strlen($reply));
			return false;
		}
		if (extension_loaded('mbstring')) {
			if ($headers['length'] > mb_strlen($payload)) {
				$user->handlingPartialPacket = true;
				$user->partialBuffer = $message;
				return false;
			}
		} else {
			if ($headers['length'] > strlen($payload)) {
				$user->handlingPartialPacket = true;
				$user->partialBuffer = $message;
				return false;
			}
		}

		$payload = $this->applyMask($headers,$payload);

		if ($headers['fin']) {
			$user->partialMessage = "";
			return $payload;
		}
		$user->partialMessage = $payload;
		return false;
	}

	protected function extractHeaders($message) {
		$header = array('fin'     => $message[0] & chr(128),
				'rsv1'    => $message[0] & chr(64),
				'rsv2'    => $message[0] & chr(32),
				'rsv3'    => $message[0] & chr(16),
				'opcode'  => ord($message[0]) & 15,
				'hasmask' => $message[1] & chr(128),
				'length'  => 0,
				'mask'    => "");
		$header['length'] = (ord($message[1]) >= 128) ? ord($message[1]) - 128 : ord($message[1]);

		if ($header['length'] == 126) {
			if ($header['hasmask']) {
				$header['mask'] = $message[4] . $message[5] . $message[6] . $message[7];
			}
			$header['length'] = ord($message[2]) * 256
			+ ord($message[3]);
		} elseif ($header['length'] == 127) {
			if ($header['hasmask']) {
				$header['mask'] = $message[10] . $message[11] . $message[12] . $message[13];
			}
			$header['length'] = ord($message[2]) * 65536 * 65536 * 65536 * 256
			+ ord($message[3]) * 65536 * 65536 * 65536
			+ ord($message[4]) * 65536 * 65536 * 256
			+ ord($message[5]) * 65536 * 65536
			+ ord($message[6]) * 65536 * 256
			+ ord($message[7]) * 65536
			+ ord($message[8]) * 256
			+ ord($message[9]);
		} elseif ($header['hasmask']) {
			$header['mask'] = $message[2] . $message[3] . $message[4] . $message[5];
		}
		//echo $this->strtohex($message);
		//$this->printHeaders($header);
		return $header;
	}

	protected function extractPayload($message,$headers) {
		$offset = 2;
		if ($headers['hasmask']) {
			$offset += 4;
		}
		if ($headers['length'] > 65535) {
			$offset += 8;
		} elseif ($headers['length'] > 125) {
			$offset += 2;
		}
		return substr($message,$offset);
	}

	protected function applyMask($headers,$payload) {
		$effectiveMask = "";
		if ($headers['hasmask']) {
			$mask = $headers['mask'];
		} else {
			return $payload;
		}

		while (strlen($effectiveMask) < strlen($payload)) {
			$effectiveMask .= $mask;
		}
		while (strlen($effectiveMask) > strlen($payload)) {
			$effectiveMask = substr($effectiveMask,0,-1);
		}
		return $effectiveMask ^ $payload;
	}
	protected function checkRSVBits($headers,$user) { // override this method if you are using an extension where the RSV bits are used.
		if (ord($headers['rsv1']) + ord($headers['rsv2']) + ord($headers['rsv3']) > 0) {
			//$this->disconnect($user); // todo: fail connection
			return true;
		}
		return false;
	}

	protected function strtohex($str) {
		$strout = "";
		for ($i = 0; $i < strlen($str); $i++) {
			$strout .= (ord($str[$i])<16) ? "0" . dechex(ord($str[$i])) : dechex(ord($str[$i]));
			$strout .= " ";
			if ($i%32 == 7) {
				$strout .= ": ";
			}
			if ($i%32 == 15) {
				$strout .= ": ";
			}
			if ($i%32 == 23) {
				$strout .= ": ";
			}
			if ($i%32 == 31) {
				$strout .= "\n";
			}
		}
		return $strout . "\n";
	}

	protected function printHeaders($headers) {
		echo "Array\n(\n";
		foreach ($headers as $key => $value) {
			if ($key == 'length' || $key == 'opcode') {
				echo "\t[$key] => $value\n\n";
			} else {
				echo "\t[$key] => ".$this->strtohex($value)."\n";

			}

		}
		echo ")\n";
	}

	public function getUserById($id)
	{
		foreach ($this->users as $u)
			if ($u->id == $id)
			return $u;
		return null;
	}

}

